发表机构
School of Physics and Electronic Technology, Liaoning Normal University; Center for Theoretical and Experimental High Energy Physics, Liaoning Normal University（辽宁师范大学物理与电子科技学院; 辽宁师范大学理论与实验高能物理中心）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
基于ATLAS对B_c^*(1S)的观测，利用相对论性Salpeter波函数研究B_c系统四个1S和2S M1辐射跃迁，揭示受抑制跃迁的径向节点抵消及夸克线过滤不对称性。
AI 中文摘要
近期ATLAS对$B_c^*(1S)$介子的观测确定了基态超精细劈裂，从而决定了$B_c^*(1S)\to B_c(1S)\gamma$的相空间。我们利用经测量的基态质量校准的相对论性Salpeter波函数，研究了四个$1S$和$2S$ M1辐射跃迁，得到$\Gamma[B_c^*(1S)\to B_c(1S)\gamma]=5.24\times10^{-2}$~keV。允许的跃迁没有表现出径向节点抵消，而受抑制的$2S\to1S$振幅是跨径向节点约二十倍抵消的残余。夸克线分辨分析显示在交叉的受抑制通道中存在强烈不对称性：$b$发射贡献经历$\mathcal O(10^2)$的内部抵消，而$\bar c$贡献保持在$\mathcal O(20)$。相应的无符号线强度表明，小的$b$流是由增强的抵消而非较小的无符号贡献产生的。未测量的$B_c^*(2S)$质量仍然是$2S\to2S$辐射宽度的主要限制。
英文摘要
The recent ATLAS observation of the $B_c^*(1S)$ meson fixes the ground-state hyperfine splitting and thereby determines the phase space for $B_c^*(1S)\to B_c(1S)γ$. We study four $1S$ and $2S$ M1 radiative transitions using relativistic Salpeter wave functions calibrated to the measured ground-state masses, obtaining $Γ[B_c^*(1S)\to B_c(1S)γ]=5.24\times10^{-2}$~keV. The allowed transitions show no radial cancellation, whereas the hindered $2S\to1S$ amplitudes are residuals of an approximately twenty-fold cancellation across the radial node. A quark-line-resolved analysis shows a strong asymmetry in the crossed hindered channel: the $b$-emission contribution undergoes an $\mathcal O(10^2)$ internal cancellation while the $\bar c$ contribution remains at $\mathcal O(20)$. The corresponding unsigned line strengths show that the small $b$-current is generated by enhanced cancellation rather than by a smaller unsigned contribution. The unmeasured $B_c^*(2S)$ mass remains the main limitation on the $2S\to2S$ radiative width.
